Authors: A. Koeck, E. Brunet, C. Griessler, T. Maier, G. Mutinati, S. Steinhauer
Affilation: AIT Austrian Institute of Technology GmbH, Austria
Pages: 306 - 309
Keywords: nanosensors, gas sensors, nanowires
Numerous applications ranging from industrial process control to personal safety systems and environmental monitoring have a strongly increasing demand for highly sensitive gas detecting devices. We present nanosensors based on SnO2-nanowires, which are extremely sensitive to the highly toxic gases SO2 and H2S. The nanowires are realized in a two-step atmospheric pressure synthesis process on Si-substrates: In a first step nanocrystalline SnO2-films with thickness ~200 nm are fabricated by a spray pyrolysis process, the second process is an annealing process at 900°C The whole SnO2-nanowire fabrication procedure is performed at atmospheric pressure and requires no vacuum. A SO2 gas concentration of 26.8 ppm results in a maximum signal of ~6% at 400°C. A H2S concentration of only 1.4 ppm results in maximum signal of 30% at 400°C. This very high sensor signalsdemonstrates extraordinary sensitivity of the nanowire sensors with a resolution in the ppb range. The sensors are able to measure concentrations well below their respective threshold limit values (SO2: 2ppm, H2S: 10ppm). The different behaviour (increase and decrease of sensor resistance) should basically allow for a clear discrimination between the two test gases.